Electrical controller for miniature trains



April 24, 1956 M. J. MURPHY ELECTRICAL CONTROLLER FOR MINIATURE TRAINSFiled Sept. 14, 1953 3 Sheets-Sheet l INVENTOR. Mari; J Muff/0 fa/ irromir April 24, 1956 M. J. MURPHY ELECTRICAL CONTROLLER FOR MINIATURETRAINS Filed Sept. 14, 1953 3 Sheets-Sheet 2 INVENTOR. Mari; M09969April 24, 1956 M. J. MURPHY 2,743,377 ELECTRICAL CONTROLLER FORMINIATURE TRAINS Filed Sept. 14. 1953 3 Sheets-Sheet 3 IN V EN TOR.Mari: Maw/y Irma/vi) United States Patent 2,743,377 ELECTRICALCONTROLLER FOR MINIATURE TRAINS Moyes J. Murphy, Monrovia, Calif.Application September 14, 1953, Serial No. 379,819

Claims. (.Cl. 3.07 -9.6)

My invention relates in general to means especially useful incontrolling the speed and direction of operation of electrically drivendevices, particularly miniature trains.

In one form, miniature trains are operated. by electricity suppliedthrough the tracks which supportthe train. For example, direct currentis furnished in varying amounts and in reversible polarity to determinenot .only the speed of the miniature .train, but also its direction ofadvance. The propulsion machinery in an. electrical miniature locomotiveusually has characteristics such that it does not start smoothly andeasily or at a scale starting acceleration and is incapable of smooth,accurately simulated operation at or near zero speed.

It is very important, particularly. to miniature train hobbyists, toreproduce, in as precise as fashion .as possible and as nearly to scaleaspossible, vthe regular operation of the prototype devices.Unfortunately, .due to the relatively high coetficient of staticfriction, due to stick factors and other related influences, it is atpresent impossible to provide .a very smooth and gradual accelerationfrom or to stopped condition or to operate continuously at a scale speedapproximating starting. or stopping. In other words, miniature trainscan not easily be operated very slowly but instead start and stopjerkily. That is true of their operation in either direction.

It is therefore an object of my invention .toprovide an electricalcontrol for miniature trains which is capable of starting the train verygradually and to scale speed and with scale acceleration from a standingstart up to a maximum velocity and down to a stopped condition.

Another object of my invention is to provide gradual acceleration of aminiature train in either direction of operation.

Another object of my invention is to provide means for controlling thespeed of operation of .a miniature train gradually and smoothly over theentire range of operation.

Another object of my invention is to provide an electri'cal controllerwhich can readily be adapted to miniature train equipment now availableand in use without change thereto.

Another object of my invention is to provide an electrical controllerwhich can readily. be operated by the usual operator without anysubstantial change. in his operating. technique.

Another object of the invention is to provide an electrical controllereconomical to manufacture, simple to service, if necessary, and whichcan readily be sold at a. price within the range of the miniature trainmarket.

A still further object of the invention is to provide an electricalcontroller which is not adversely affected, as by overheating or thelike, by protractedoperation at any speed.

An additional obj ct of the invention is in general to provide animproved electrical controller for miniature trains.

Other objects, together with the foregoing, are attained in theembodiment of the invention described in the accompanying descriptionand illustrated in the accompanying drawings in. which:

Figure l is an isometric view, portions being broken away, showing theelectrical controller in its normal position of use in connection with aminiature train.

Figure 2 is a plan of the controller, a portionof the housing beingbroken away to disclose the interior.

Figure 3 is a cross section, the plane of which is indicated by the line3-3 of Figure 2.

Figure 4 is a cross section, the plane of which :is indicated by theline 44 of Figure 3.

Figure 5 is a view showing the various layers of the arm beforeassembly.

Figure 6 is a view similar to- Figure 4 with certain portions removedfor clarity and showing the arm in one extreme position of operation.

Figure 7 is a diagrammatic plan of the rotary commutator illustratingvarious brush positions thereon.

Figure 8 is an end view of the electrical controller.

While the electrical controller of my invention is adapted for use inmany fields for controlling electrical equipment, it is especiallyadapted for the control .of miniature trains and. is therefore describedin that connection. In the usual instance, the miniature train includesa locomotive 6, for example, which is provided with any suitable sort ofelectric motor, in the present instance, the motor being a directcurrent motor. The locomotive 6 operates on a miniature track 7, havingmetallic conductor rails 8 and 9 included therein The rails areinsulated from each other by miniature ties 1.0 and serve, byconnections in the locomotive 6, as .condoctors to supply electricity tothe driving motor for the locomotive, the polarity of ,the rails '7 and.8 being reversed in order to reverse the motor to act as a brake or torun in the opposite direction.

Supply of current ,to the rails 7 and 8 is through a pair of conductors12 and 13, emanating from an electrical controller 14 constructed inaccordance with the invention. The controller 14 is supplied withcurrent of two sorts. T ere is a supply of alternating current throughleads 16 and 17, this current customarily being supplied atapproximately to volts, and having a standard frequency, for example, 60cycles per second. The conductors 16 and 17 have leads 18 and 19 extending to a suitable current rectifier 21 for affording a supply of directcurrent through leads 22 and 23 to the electrical controller 1.4. Ifdesired, the rectifier 21 .can be replaced by .a storage battery or anyother suitable source of direct current supply, in which instance theleads 18 .and 1 9 are omitted. In any case, the electrical controller 14is supplied with alternating. current through the leads l6. and 17 andis supplied with direct current through the leads 22 and 23. The voltageandamperage of the direct current supplied through the leads 22 and 23are preferably those customarily utilized for the operation of theminiature locomotive 6.

The controller housing 14 preferably incorporates a top panel 31, ofnon-conducting material, on which a frame 32 is mounted. The framepreferably includesa mounting plate 33 and a top plate 34, togetherconstituting a cover, and secured in. juxtaposition with an interveningsound absorbent .and cushioning. material in the form of an interposedsheet 36. The top plate 34. is .pro.- vided with a number of apertures37 through which access is had. to fastening screws 38: for securing theframe '32 to the housing 14. The cover is held together by frame posts39- and appropriate fastenings 41 so that an appropriate mounting isafforded.

The'depending posts 39, four in number, at their lower endsserve assupports'for a-frame plate 42 secured in positionby fastenings 43. Atone extremity, the frame plate 42 is extended to serve as a mounting forinsulating layers 44 and 46, held in position with respect to aperturesthrough the frame plate 42' by bushings 47 formed integrally withinsulating tubes 48 upstanding from the frame plate 42. Of-the fourinsulating tubes 48, the outer two are secured in position by throughbolts 49 and 51, having fastening nuts 52 securing them in position, andalso having jam nuts 53-to act as terminals for the conductors 22 and23. One of the two central members 48 is longer than the others and thetwo are-held in position by through bolts- 54 and 56 having jam .nuts 57and lock nuts 58 thereon to serve as terminals for the conductors 12 and13.

Also mounted on the .top plate 34, for rotation with respect thereto, isa shaft 61 having a sleeve 62 secured thereto by a through pin 63. A hub64 with an extended bushing thereonfits overthe shaft 61 and is jammedagainst the sleeve 62, except for an-intervening anti-friction washer66, by an axial screw 67. A set screw 68 prevents rotation of the hub 64with respect to the shaft 61. Also jammed in good supportingrelationship with the top plate 34, is an intervening friction washer 69and the central ring 71 of an operating lever 72. The lever 72, at thering portion 71, is preferably secured by brazing, silver soldering orthe like, to the hub 64 and is upwardly offset so as to be spaced aconvenient distance from the top plate 34. It ends in a handle portion73 including a through finger aperture 74, having rounded edges. Withthis construction, the lever 72 can be swung with respect to the coverabout the axis of the shaft 61, the washers 66 and 69 serving not onlyto assist in the mounting but as friction supports so that the lever iseasily rotated or swung, yet will stay in any set position.

The sleeve 62 depends through the housing 14 and carries a stub shaft 76for rotation therewith, the fastening being effectuated by a pin 78. Thestub shaft 76 is axially bored to receive an electrical brush 79 urgedin a downward axial direction by a coil spring 81.

Also carried by the stub shaft 76 is a packet of layers constituting anarm 82. The top layer 83 of the packet is a metallic conductor and issecured by brazing, soldering or welding to'the stub shaft 76.Immediately beneath the layer 83 is a pair of insulating layers 84 and86 and below them is a conducting, lower layer 87. All of these layersare of substantiallythe same outline contour, as shown especially inFigure 4, and constitute substantially a circular disc with a radialprojection. The packet is mechanically secured together with the upperlayer 83 electrically insulated from the lower layer 87 by fasten ings88 which alternately engage the lower and upper layers but invariablyengage the intermediate insulating layers 84 and 86. The fastenings arespaced from the layers they do not contact by apertures 89 therein ofadequate insulating dimensions. Furthermore, the lower layer 87 has acentral aperture of suificient dimension to be electrically separatefrom the stub shaft 76. Also, the insulating layers 84 and 86 have largecentral apertures for convenience in assembly and to avoid the filletleft by the welding or brazing operation around the stub shaft 76. Evenfurther, while the various layers in the packet are of the generalconformation indicated, the lower layer 87 is somewhat incomplete inthat it stops just short of a diameter on the axis of the stub shaft 76,as shown in Figures 4 and 5, and is supplemented by a co-planarextension layer 91. This completes the envelope contour but itself stopssomewhat short of a diameter to leave what amounts to a diametricalgroove 92 or gap in the lower surface of the arm, a portion of theinsulating layer 86 being thereby exposed.

The radially extended portion of the arm carries a.

brush 93 mounted in a socket 94 of conducting material and carrying aspring 96 urging the brush 93 outwardly. The socket 94 is shouldered andgrooved to receive a fastening ring 97 on its lower end and to confinean insulating disc 98 near its center. The upper layer 83 is 4 providedwith an aperture suificiently spaced from the socket 94, guided by theclose fitting insulating layers 84 and 86, so that there is noelectrical contact between the upper layer 83 and the socket 94. Thereis, however, a close metallic contact not only between the socket 94 andthe lower layer 87, but also between the fastening ring 97 and thesocket so that a firm electrical connection is so established betweenthe brush 93 and the lower layer 87.

Carried on the frame plate 42 in operative relationship with the brushes79 and 93 is a rotary commutator 101. This, preferably, is in the formof a disc 102 of metal over which an insulating sheet 103 is disposed.Superposed on the insulating sheet is a conducting metallic disc 104 ofgenerally circular outline, having, however, two tangent circularapertures 106 and 107 (Figure 6) cut therefrom. In the apertures aredisposed two insulating discs 108 and 109 secured in position byfastenings 111 insulated from but secured in the disc 102, while similarfastenings 112 hold the conducting disc 104 in position. The disc 102 isformed with a central hub 113 fitting over a drive shaft 114 and securedthereto by a set screw '116.

The drive shaft 114 is rotated by means of an electric motor 117 of anycustomary kind and usually is an alternating current, synchronous motorwith or without a gear reduction to give any desired speed of operationof the shaft 114. In the present instance, the speed of rotation is ofthe order of 3,600 revolutions per minute.

.The motor is supported on the plate 42 by appropriate fastenings 118and is connected to insulated terminals 119 and 120 serving as theterminals for the conductors 18 and .19, respectively.

One of the electrical paths through the structure is from the conductor22 to the terminal 24 and through the bolt 49 to a spring primarycontactor 126 secured thereto and extending approximately tangent to thearm 82. The contactor has a spherical end 127 adapted to be seated inthe groove 92 when the arm is in the position illustrated in Figure 4,for example. In that position of the parts, the primary contactor 126 isagainst insulation and the circuit is interrupted. If the arm is movedin either direction, however, the current then has a path into eitherthe lower layer 87 or the extension layer 91. Whichever layer formsthepath of the current, the other plate is then in touch with anotherprimary contactor 128 having'a similar spherical end 129 thereon andbeing fastened to the bolt 51.

The extension layer 91 is contacted by a secondary contactor 131 on thebolt 56 and having a spherical end 132 thereon and identical in shapewith the primary contactors 126 and 128 except that it is folded over totouch the smooth periphery of the extension layer 91. A similarsecondary contactor 133 is supported on the terminal 54 and has aspherical end 134 in abutment with the top layer 83 of the arm. If,therefore, a circuit is completed between the lower layer 87 and theupper layer 83, the. various primary and secondary contactors and theextension plate 91, there is provided a polarity reversing device. Thus,by manipulation of the lever 72, if the terminal bolts 49 and 51 arerespectively positive and negative, the terminal bolts 54 and 56 can bemade respectively positive and negative or negative and positive. Hence,the polarity of the direct current supplied to the tracks 8 or 9 isselected and reversed and the direction of operation of the engine 6 isestablished and changed. Intermediate the direction changing positionsis a neutral, or zero current, or off position.

Current from the bottom layer 87; for example, is conducted to the brush93 and in the central position of the arm 82, is blocked from furthertravel since the theoretical point contact of the brush 93 is exactly atthe theoretical point of intersection of the tangent insulating discs108 and 109 and so there is no current path. Since in practice the brush93 has a small area of contact rather'than the theoretical pointcontact, the insulating discs 108 and 1 09 are made not exactly tangent:but interfere slightly so that there is established an off or neutralarea.

When the lever 72 and the arm:82 are swung to .either side of centralposition, then the brush 93 is swung into the path of contact of part ofthe conducting disc 104. Current flows then through that disc to thebrush '79, which is always in contact with the -continuous metallicperiphery or marginal portion of the disc 104. The current then flowsthrough the stub shaft 76 into the upper layer '83 and'to the secondarycontactor 133. Thus, the circuit is completed, although it is completedin the reverse direction in the event the primary contactor 128happensto :be in abutment with the layer 87 and the primary contactor126 is in abutment with the extension layer 91.

In the operation of the device, both of the circuitsare energized sothat the electric motor 117 rotates the disc 102 at a rapid rate. Whenthe lever 72 is in a central, oil? or neutral position, the circuit isinterrupted with the spherical ends 127 and 129 of the primarycontactors 126 and 128 in an insulated position and also with the brush93 in an insulated position.

In the event it is considered that it is not necessary to have anelectrical gap at the ends of the primary contactors 128 and 126 whenthe groove 92 is in the central position, then the proportions of thegroove 92 can be made such that the springy primary contactors and theirspherical ends serve with the groove and the adjacent layers as a detentmechanism, yieldingly centralizing the lever 72 and the arm 82.

In either case, the brush 93, in its central position, is out of contactwith an electrical conductor. However, as the lever 72 is swung to oneside or the other, as shown especially in Figure 7, increasing amountsof electrical conductor abut the brush. as it leaves center position.Current flow is possible just after the brush 93 leaves central positionin either direction, the duration of current flow for each revolution ofthe commutator 101 depending upon the displaced position of the arm 82.Toward the center, only a small fraction of one revolution is given overto current conduction, the remaining part of the revolution being acurrent interruption as the brush 93 rides over the insulating discs 108and 109.

As the brush swings farther and farther away from center position, theamount of conduction time is increased and the amount of insulation timeis decreased until the brush gets near the marginal periphery of thedisc. There it runs on a continuous conducting portion of the disc 104and there is no interruption at all. There is thus provided a variationin current impulse length per revolution of the commutator from zero atthe center through very short impulses near the center, throughincreasingly long impulses toward the edge, until finally at the edgethere is no interruption whatsoever but there is continuous conduction.

The particular characteristics or proportion of current fiow time tocurrent interrupted time for any displaced position of the brush dependsupon the shape of the insulators 108 and 109. These are convenientlymade circular discs, although they can be segments or otherconfigurations. There is thus provided a structure giving a variationfrom no impulses, tluough current impulses of varying duration tocontinuous current at the control of the operator. The current impulsesare available and effective in either direction of operation, due to theoperation of the polarity reversing mechanism.

The operator, by putting his finger on the lever 72 in or near theaperture 74 and by swinging the lever either way, to the right or to theleft, can control the direction of operation of the train 6 and bycontrolling the amount of displacement of the lever from centralposition can control the speed of the train very accurately. In fact,the impulses are of sufiicient strength when they are flowing to :breakloose or overcome the stick point or static friction of :the train andits driving motor, but are of sufliciently short duration .or are spacedsufficiently far apart so that the net speed of the train 6 is verysmall and is according to scale. It is therefore possible tostart thetrain smoothly and to accelerate it very slowly in accordance withaccurate scale performance up to its maximum speed when there is nolonger any current interruption. Similarly, the train can be braked andslowed down very smoothly and continuously to a smooth stop withoutjerk, and this from either direction of operation at maximum speed. In apractical example, with ;a locomotive and tracks of approximately actualsize -("?HO gauge) it is possible to operate a locomotive, at an actualspeed .of advance of one-quarter inch per minute, which is equivalent toa scale speed of mile per hour. The appearanceof the operation isof-continuous motion, despite the fact that the impulses are separatedfor part :of the time, because of the effect of momentum of thelocomotive 6, and because the impulses are of quite rapid frequency.

What is claimed is:

1. An electrical controller for miniature trains comprising a frame; anarm; means for mounting said arm on said frame for swinging movementabout an axis; a pair of brushes on said arm, one of said brushes beingon said axis; a rotary disc commutator on said frame in contact withsaid brushes; said commutator having a peripheral continuous conductingportion, a central continuous insulating portion and an alternatelyconducting and insulating portion; means on said frame for rotating saidcommutator with said continuous conducting portion in contact with saidone of said brushes; means on said arm for insulating said brushes fromeach other; and means for swinging said arm to move the other of saidbrushes over said various commutator portions.

2. An electrical controller for miniature trains comprising a frame; adisc commutator on said frame; said commutator having a peripheralcontinuous conducting portion, a central continuous insulating portionand an alternately conducting and insulating portion; means on saidframe for rotating said commutator about a rotational axis; an arm; apair of brushes on said arm; means on said arm for insulating saidbrushes from each other; and means for mounting said arm on said framefor swinging movement about one of said brushes as a center and withsaid one brush in contact with said continuously conducting portion andwith said other brush swinging over said rotational axis in contact withsaid commutator.

3. An electrical controller for miniature trains comprising a frame, arotary disc commutator on said frame, said frame having a planeconducting surface continuous around the periphery of said disc andinterrupted in part by an insulating surface extending across therotational center of said commutator and varying in circumferentiallymeasured dimensions at varying radially measured distances from saidcenter, means on said frame for rotating said commutator about saidcenter, an arm, means for mounting said arm on said frame for swingingmovement in a plane parallel to the plane of said disc and about an axiswithin the periphery of said disc, a first brush on said arm disposed onthe swinging axis of said arm and extending into abutment with saidcontinuous conducting surface, a second brush on said arm disposed toswing through a position coincident with the rotational axis of saiddisc and extending into abutment with the surface of said disc, andmeans on said arm for insulating said first and second brushes from eachother.

4. An electrical controller for miniature trains comprising a frame, adisc commutator on said frame, said commutator having a peripherallycontinuous conducting surface interrupted in part toward the center ofsaid disc commutator by an insulating surface, means on said frame forrotating said commutator, an arm, a pair of brushes on said am, means onsaid arm for insulating said brushes from each other, and means formounting said arm on said frame for swinging movement parallel to theplane of said disc commutator, said mounting being in a location todispose one of said brushes for continuous contact with saidperipherally continuous conducting surface and the other of said brushesfor contact alternately with said peripherally continuous conductingsurface and said insulating surface.

5. An electrical controller for miniature trains comprising a frame, adisc commutator on said frame, said commutator having a planarcontinuous conducting surface interrupted in part by an insulatingsurface extending across the rotational center of said commutator, meanson said frame for rotating said commutator, an arm, a pair of brushes onsaid arm, means on said arm for insulating said brushes from each other,means for mounting said arm on said frame for swinging movement with oneof said brushes in contact with said continuous conducting surface andthe other of said brushes in contact with said surfaces and passing overthe rotational center of said commutator, means for including saidcommutator conducting surface and said brushes in an electrical circuit,first polarity reversing switch contacts for said circuit and disposedon said arm, second polarity reversing switch contacts for said circuitand disposed on said frame, and means for abutting said first switchcontacts with said second switch contacts for one polarity when said armis on one side of said rotational center and for abutting said firstswitch contacts with said second switch contacts for the other polaritywhen said arm is on the other side of said rotational center.

References Cited in the file of this patent UNITED STATES PATENTS

